Filtering toxic compounds from blood has been an area of great importance for human health. Filters for adsorption of toxic compounds from blood are known in the art. An example is the use of extracorporeal filters to remove chemotherapeutic drugs from the blood stream during cancer treatments such as in hepatic chemosaturation therapy. This therapy also known as percutaneous hepatic perfusion (PHP) delivers ultra-high doses of intra-arterial chemotherapy directly into the isolated liver, saturating both the liver and the tumor cells. The blood from the liver is drained through an isolation-aspiration catheter, and then directed outside the body to specially designed, and often proprietary, filters which reduce the concentration of chemotherapeutic agent before this blood is returned to the body. The potential of chemosaturation therapy includes: the ability to administer higher doses of chemotherapeutic agent to a particular organ than could be delivered with traditional systemic-intravenous methods while significantly reducing systemic exposure to the high dose levels.
The filters used to absorb the drug from the blood are incorporated in an extracorporeal circuit. The blood drained from the liver through the isolation aspiration catheter is pumped by a venous bypass pump, such as is used in heart bypass surgery, through a filter or set of filters. The outlet of the filter(s) is connected by a tube set to a return catheter inserted in a central vein, through which the cleaned blood is returned to the patient's circulatory system. In use, the filter(s) are required to absorb drug at an efficiency which protect the patient's systemic circulation from toxic side effects of high drug concentrations. During use with certain drugs such as Melphalan Hydrochloride, poor filtration can cause side effects such as anemia, thrombocytopenia, neutropenia, together commonly known as Myelo Suppression. Other drugs at high concentrations have risk of cardio toxicities if poor filtration fails to reduce systemic concentrations to safe levels.
Filters, pumps, and connecting tubing are typically set up and assembled by a perfusionist, or other technician, prior to the case. Filters may be clamped or taped to equipment such as IV poles. Multiple filters are often used to aid efficiency. Many times hardware such as lab clamps can become misplaced between cases wasting time to find or forcing the technician to improvise a support method at the last minute.
The system, including filters, is connected to catheters for withdrawal and return of blood to the patient. For the entire system all surfaces exposed to body fluids should be kept sterile.
Prior to use, the filters, blood circuit tube set, and pump are prepared for the procedure. The filters are required to be primed with saline to remove all air from the filter media and to be flushed with saline to remove any fine particulate in the media prior to blood being introduced to the circuit. Proper priming is critical to filter performance. Removing air is necessary to eliminate the potential for air to be infused into the patient. Also, any air left in the filter reduces the surface area that blood will contact the filter media thus reducing filter efficiency.